[Mne_analysis] Auditory ROI

[Alexandre Gramfort]

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hi,

> This is cancellation phenomenon in signal processing. To be more specific in neuroimaging of MEG/EEG, when you send the same sound simultaneously to each ear of a subject, like you mentioned single stereo tones, there will be temporally correlated sources on bilateral A1s in the MEG or EEG signals recorded from the subject. Highly temporally correlated sources in an MEG or an EEG will cause the problem you mentioned. Furthermore, this phenomenon can be explained by math. So, if you want to know more, I can give you some references.

I think that Noa is using MNE-dSPM so I am not sure it is a problem of
correlated sources.

> Solution to this problem: Noa, you need to use advanced source localization algorithms to localize the true source grids and reconstruct the distortionless time-courses of correlated sources. But I am not familiar with MNE, so I don't know which advanced algorithms are available in MNE software to address this problem. However, I know some available algorithms in other toolboxes.

see what MNE has in store:
http://martinos.org/mne/stable/auto_examples/index.html

you can use MNE/dSPM/sLORETA/eLORETA with make_inverse_operator
you have most beamformers (make_lcmv, make_dics) as well as
sparsity based solvers that output dipole sets such as mixed_norm,
tf_mixed_norm, music, gamma_map etc.

Alex